The present invention is directed to a selectively operable multiple needle sewing machine and more specifically to a thread clamping device for selectively clamping the threads leading to the inoperative needles to prevent entanglement of said threads with the thread leading to the operative needle upon oscillation of the thread take-up lever.
In the conventional selectively operable multiple needle sewing machine 10 shown in FIG. 1, any one of the three needles 11, 12, and 13, may be selected for reciprocation by any suitable means (not shown) while the other two needles remain inactive. The threads 14, 15, and 16, leading to the needles 11, 12 and 13, respectively, pass through holes 17, 18, and 19 formed in a common take-up lever 20. The holes 17, 18, and 19, are each formed in a separate extension of the common take-up lever 20, thereby substantially increasing the mass of the oscillating take-up lever 20. As a result of the increased mass of the oscillating take-up lever 20, it is impossible to operate the sewing machine at high speeds. Furthermore, even though only a single needle is selectively operated with a reciprocating motion, all of the threads are simultaneously moved in a vertical direction in accordance with the oscillating movement of the take-up lever 20 during a sewing operation. Thus, the three threads tend to become tangled with each other during the operation of the sewing machine.